diff --git a/pyrogram/errors/__init__.py b/pyrogram/errors/__init__.py
index 1b94700f..514e7a12 100644
--- a/pyrogram/errors/__init__.py
+++ b/pyrogram/errors/__init__.py
@@ -18,3 +18,24 @@
 
 from .exceptions import *
 from .rpc_error import UnknownError
+
+
+class BadMsgNotification(Exception):
+    descriptions = {
+        16: "The msg_id is too low, the client time has to be synchronized.",
+        17: "The msg_id is too high, the client time has to be synchronized.",
+        18: "Incorrect two lower order of the msg_id bits, the server expects the client message "
+            "msg_id to be divisible by 4.",
+        19: "The container msg_id is the same as the msg_id of a previously received message.",
+        20: "The message is too old, it cannot be verified by the server.",
+        32: "The msg_seqno is too low.",
+        33: "The msg_seqno is too high.",
+        34: "An even msg_seqno was expected, but an odd one was received.",
+        35: "An odd msg_seqno was expected, but an even one was received.",
+        48: "Incorrect server salt.",
+        64: "Invalid container."
+    }
+
+    def __init__(self, code):
+        description = self.descriptions.get(code, "Unknown error code")
+        super().__init__(f"[{code}] {description}")
diff --git a/pyrogram/session/session.py b/pyrogram/session/session.py
index 721586a0..06df2125 100644
--- a/pyrogram/session/session.py
+++ b/pyrogram/session/session.py
@@ -29,7 +29,9 @@ from pyrogram import __copyright__, __license__, __version__
 from pyrogram import raw
 from pyrogram.connection import Connection
 from pyrogram.crypto import mtproto
-from pyrogram.errors import RPCError, InternalServerError, AuthKeyDuplicated, FloodWait, ServiceUnavailable
+from pyrogram.errors import (
+    RPCError, InternalServerError, AuthKeyDuplicated, FloodWait, ServiceUnavailable, BadMsgNotification
+)
 from pyrogram.raw.all import layer
 from pyrogram.raw.core import TLObject, MsgContainer, Int, FutureSalt, FutureSalts
 from .internals import MsgId, MsgFactory
@@ -44,7 +46,6 @@ class Result:
 
 
 class Session:
-    INITIAL_SALT = 0x616e67656c696361
     START_TIMEOUT = 1
     WAIT_TIMEOUT = 15
     SLEEP_THRESHOLD = 10
@@ -54,20 +55,6 @@ class Session:
 
     notice_displayed = False
 
-    BAD_MSG_DESCRIPTION = {
-        16: "[16] msg_id too low, the client time has to be synchronized",
-        17: "[17] msg_id too high, the client time has to be synchronized",
-        18: "[18] incorrect two lower order msg_id bits, the server expects client message msg_id to be divisible by 4",
-        19: "[19] container msg_id is the same as msg_id of a previously received message",
-        20: "[20] message too old, it cannot be verified by the server",
-        32: "[32] msg_seqno too low",
-        33: "[33] msg_seqno too high",
-        34: "[34] an even msg_seqno expected, but odd received",
-        35: "[35] odd msg_seqno expected, but even received",
-        48: "[48] incorrect server salt",
-        64: "[64] invalid container"
-    }
-
     def __init__(
         self,
         client: "pyrogram.Client",
@@ -129,7 +116,7 @@ class Session:
 
                 self.network_task = self.loop.create_task(self.network_worker())
 
-                self.current_salt = FutureSalt(0, 0, Session.INITIAL_SALT)
+                self.current_salt = FutureSalt(0, 0, 0)
                 self.current_salt = FutureSalt(
                     0, 0,
                     (await self._send(
@@ -243,9 +230,7 @@ class Session:
                 MsgId.set_server_time(msg.msg_id / (2 ** 32))
 
             if msg.seq_no % 2 != 0:
-                if msg.msg_id in self.pending_acks:
-                    continue
-                else:
+                if msg.msg_id not in self.pending_acks:
                     self.pending_acks.add(msg.msg_id)
 
             if isinstance(msg.body, (raw.types.MsgDetailedInfo, raw.types.MsgNewDetailedInfo)):
@@ -395,10 +380,7 @@ class Session:
 
                 RPCError.raise_it(result, type(data))
             elif isinstance(result, raw.types.BadMsgNotification):
-                raise Exception(self.BAD_MSG_DESCRIPTION.get(
-                    result.error_code,
-                    f"Error code {result.error_code}"
-                ))
+                raise BadMsgNotification(result.error_code)
             else:
                 return result